Clindamycin-2-phosphate (7(S)-chloro-7-deoxylincomycin-2-phosphate) is a new semi-synthetic antibiotic. It is recognized that the drug itself is inactive against bacteria in vitro but it is hydrolyzed rapidly to active clindamycin, drug intramuscular or intravenous administration. Clindamycin-2-phosphate was administrated intravenously to seven patients with infections, except one intramuscularly, 300 approximately 600 mg, every 8 or 12 hours a day, for 2 approximately 12 days. Three patients (1 bacterial pneumonia, 1 chronic bronchitis and 1 urinary tract infection due to E. coli) recovered from their infection; one patient (bacterial infection in bronchiectasis) partially responded; and three patients (1 urinary tract infection due to E. coli, 1 pneumonia due to Mycoplasma pneumoniae and 1 patient with mycoplasmal pneumonia and acute biliary tract infection) failed to respond to the drug. No remarkable side effect was noted except pain at intramuscular injection site in one patient.